The BSA Bantam is a two-stroke unit construction motorcycle that was produced by the Birmingham Small Arms Company (BSA) from 1948 (as a 125 cc) until 1971 (as a 175 cc). Exact production figures are unknown, but it was over 250,000 and some estimates place the number closer to half a million.
The engine is a unit construction (engine and gearbox of one piece) single cylinder 2 stroke. The barrel is cast iron while the head is alloy. The gearbox was initially three speeds, later versions went to four, fed through a “wet” clutch. Ignition was of two types a Lucas battery powered coil in earlier machines or a magneto by Wipac. The magneto was on a composite assembly sitting within the flywheel with its magnet inserts; windings gave power either directly to the lights (with a dry cell for when the engine was stopped) or through a rectifier into a lead acid battery. The early D1s had “fish tail” styled exhausts but this was replaced with the more conventional cylindrical silencer. High-level exhausts were made for the trials and off-road models, in which the only electrics are the magneto-powered ignition.
The BSA A65R Rocket was one of a series of unit construction twin cylinder Birmingham Small Arms Company (BSA) motorcycles made in the 1960s. A version branded as the A65 ‘Thunderbolt Rocket’ was aimed at the US market. The A65R Rocket was produced from 1964 but was stopped in 1965 when all development at BSA was halted by financial difficulties.
The A65R was a development of the old model range led by Bob Fearon, Managing Director and General Manager of BSA and Chief Development Engineer Bert Perrigo they developed the unit construction Star twins. To make the A65R more of a ‘sports version’ of the original BSA A65 Star (and in anticipation of more stringent noise control legislation) it was given ‘siamesed’ 2 into 1 exhaust pipes with a special baffle, as well as chrome plated mudguards and headlight brackets. Able to cruise at 85 mph (137 km/h) and with a top speed of 108 mph (174 km/h) it was sold as the fastest BSA in production. A special version of the A65 branded as the A65T/R ‘Thunderbolt Rocket’ was aimed at the US market and featured high rise handlebars and a smaller fuel tank.
By 1965 competition from motorcycle producers such as Honda were eroding BSA’s previously rising sales figures. BSA’s marketing team was slow to respond and new motorcycle development contributed to substantial losses, so by 1972 the company was absorbed into Manganese Bronze Holdings in a rescue plan initiated by the Department of Industry. A plan to combine Norton, BSA and Triumph failed through poor industrial relations and the BSA factories closed.